#resources/linux/users

Linux Users & `Sudo` :

`Sudoers` File

Location: /etc/sudoers
Controls who can use sudo (run commands as admin).
Example:
```
%sudo   ALL=(ALL:ALL) ALL
```
→ Anyone in the sudo group can run any command as admin.
Always edit with:
```
sudo visudo
```

Useful Commands

Check what you can run with sudo:
```
sudo -l
```

Become root:

sudo su     # root shell
sudo -i     # root login shell

See who’s in the sudo group:
```
grep 'sudo' /etc/group
```

Pasted image 20250618211118.png

Key Files

/etc/passwd → Lists all users (username, home folder, shell).
/etc/shadow → Stores encrypted passwords (only root can read).
/etc/group → Lists groups and members.

Pentesting/CTF Tip

/etc/passwd shows usernames and services.
/etc/shadow (if you can read it) has password hashes that attackers might crack.
Knowing users = important step in hacking challenges.